1. Field of Invention
The invention relates to a cryogenic fluid conduit coupling device for connecting two cryogenic fluid conduits to allow fluid communication therebetween.
2. Description of Related Art
A cryogenic fluid is a fluid capable of producing very low temperatures. Cryogenic fluids, such as, for example, carbon dioxide and nitrogen, have very low sublimation and/or boiling points. They are capable of absorbing very large amounts of heat to produce very low temperatures in adjacent materials when they change from one state to another, for example, from a liquid or solid state to a gaseous state. In addition, when a compressed gaseous cryogenic fluid is allowed to expand, its temperature decreases and the cryogenic fluid is capable of cooling adjacent materials by absorbing heat from the materials as the compressed fluid expands.
Cryogenic fluids can be useful, for example, in heat exchange apparatus, such as that disclosed in simultaneously filed co-pending U.S. application Ser. No. 09/039,443. However, a coupling device is often necessary in order to couple the conduit of the cryogenic fluid source to the heat exchange apparatus.
Many coupling devices are known for coupling two fluid conduits. For example, U.S. Pat. No. 1,117,762 to Barcus discloses a device for connecting a section of a hose or conduit to another section or to a hydrant. The device includes cylindrical outer coupling part 1, which receives a tapered end portion 2" of cylindrical inner coupling part 2. The flow path of the coupling part 1 includes an expansion chamber within which a spring 20 is disposed.
U.S. Pat. No. 4,566,489 to Knapp et al. discloses a hydraulic coupling apparatus for connecting fluid lines of a fluid handling system. The coupling apparatus includes a male coupler 12 and a female coupler 14. Sleeve portion 16 of the female coupler 14 receives tip portion 17 of the male coupler 12 to assemble the couplers together. An expansion chamber is formed within sleeve 16 as a result of engagement of a pair of flanges 31 and 32 provided on the outer surface of the tip portion 17 of the male coupler and stop surfaces 41, 42.
U.S. Pat. No. 4,566,723 to Schulze et al. discloses a coupler for hose lines of high-pressure cleaning equipment and high-pressure spraying equipment. The coupler includes a hose nipple 2 connected to a hose and surrounded by a sleeve 7. A connector piece 22 also connected to a hose is received within sleeve 7 to mate with nozzle 2. Once introduced into the sleeve 7, a helical compression spring 9 pushes the connector piece away from the hose nipple 2 creating an expansion chamber within the hose nipple 2.
Each of the above coupling devices is inadequate for use with cryogenic fluids. Fluctuation in the cross-sectional area of the fluid flow path causes compression and/or expansion of the fluid flowing therethrough. Such compression and/or expansion of the fluid results in cold and hot spots in the fluid flow path, which will structurally weaken the coupling device over time and may cause solidification of the fluid causing blockage of the fluid flow path.